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Bounty Ended with no winning answer by Harry Gindi
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Harry Gindi
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Recall that a morphism of rings $R\to S$ is called (essentially) smooth if it is formally smooth and (essentially) finitely presented.

(Note: $R\to S$ is essentially finitely presented provided that $S$ is the localization of some finitely
presented $R$-algebra $T$ at some multiplicative system $A \subset T$, that is, $S=A^{-1}T$.)

In class, our professor said that working with smooth or essentially smooth morphisms yields an effectively equivalent theory. This motivates my question: Is there a general technique to lift results from the smooth case to the essentially smooth case?

For instance, if $R$ is reducedEdit: According to Mel, andevery essentially smooth morphism $R\to S$ isis a localization of a smooth morphism. However, then $S$this direction is reduced. It turns out thatmuch more involved than the same factother direction, which is true for essentially smooth mapsimmediate from the definitions. Is there a good way to "lift" Anyway, this resultwould be the answer to the more general case?question.

Recall that a morphism of rings $R\to S$ is called (essentially) smooth if it is formally smooth and (essentially) finitely presented.

(Note: $R\to S$ is essentially finitely presented provided that $S$ is the localization of some finitely
presented $R$-algebra $T$ at some multiplicative system $A \subset T$, that is, $S=A^{-1}T$.)

In class, our professor said that working with smooth or essentially smooth morphisms yields an effectively equivalent theory. This motivates my question: Is there a general technique to lift results from the smooth case to the essentially smooth case?

For instance, if $R$ is reduced, and $R\to S$ is smooth, then $S$ is reduced. It turns out that the same fact is true for essentially smooth maps. Is there a good way to "lift" this result to the more general case?

Recall that a morphism of rings $R\to S$ is called (essentially) smooth if it is formally smooth and (essentially) finitely presented.

(Note: $R\to S$ is essentially finitely presented provided that $S$ is the localization of some finitely
presented $R$-algebra $T$ at some multiplicative system $A \subset T$, that is, $S=A^{-1}T$.)

In class, our professor said that working with smooth or essentially smooth morphisms yields an effectively equivalent theory. This motivates my question: Is there a general technique to lift results from the smooth case to the essentially smooth case?

Edit: According to Mel, every essentially smooth morphism is a localization of a smooth morphism. However, this direction is much more involved than the other direction, which is immediate from the definitions. Anyway, this would be the answer to the question.

Bounty Started worth 250 reputation by Harry Gindi
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Harry Gindi
  • 19.6k
  • 16
  • 123
  • 215

Recall that a morphism of rings $R\to S$ is called (essentially) smooth if it is formally smooth and (essentially) finitely presented.

(Note: $R\to S$ is essentially finitely presented provided that $S$ is the localization of some finitely
presented $R$-algebra $T$ at some multiplicative system $A \subset T$, that is, $S=A^{-1}T$.)

In class, our professor said that working with smooth or essentially smooth morphisms yields an effectively equivalent theory. This motivates my question: Is there a general waytechnique to lift results from the smooth case to the essentially smooth case?

For instance, if $R$ is reduced, and $R\to S$ is smooth, then $S$ is reduced. It turns out that the same fact is true for essentially smooth maps. Is there a good way to "lift" this result to the more general case?

Recall that a morphism of rings $R\to S$ is called (essentially) smooth if it is formally smooth and (essentially) finitely presented.

(Note: $R\to S$ is essentially finitely presented provided that $S$ is the localization of some finitely
presented $R$-algebra $T$ at some multiplicative system $A \subset T$, that is, $S=A^{-1}T$.)

In class, our professor said that working with smooth or essentially smooth morphisms yields an effectively equivalent theory. This motivates my question: Is there a general way to lift results from the smooth case to the essentially smooth case?

For instance, if $R$ is reduced, and $R\to S$ is smooth, then $S$ is reduced. It turns out that the same fact is true for essentially smooth maps. Is there a good way to "lift" this result to the more general case?

Recall that a morphism of rings $R\to S$ is called (essentially) smooth if it is formally smooth and (essentially) finitely presented.

(Note: $R\to S$ is essentially finitely presented provided that $S$ is the localization of some finitely
presented $R$-algebra $T$ at some multiplicative system $A \subset T$, that is, $S=A^{-1}T$.)

In class, our professor said that working with smooth or essentially smooth morphisms yields an effectively equivalent theory. This motivates my question: Is there a general technique to lift results from the smooth case to the essentially smooth case?

For instance, if $R$ is reduced, and $R\to S$ is smooth, then $S$ is reduced. It turns out that the same fact is true for essentially smooth maps. Is there a good way to "lift" this result to the more general case?

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Harry Gindi
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Do essentially Lifting results from smooth ring maps factor into a composition of ato essentially smooth map and a localization?maps.

ARecall that a morphism of rings $R\to S$ is called essentially smooth(essentially) smooth if it is formally smooth and essentially finitely presented, where essentially(essentially) finitely presented means.

(Note: $R\to S$ is essentially finitely presented provided that $S$ is the localization of some finitely presented
presented $R$-algebra $T$ at some multiplicative system $A \subset T$, that is, $S=A^{-1}T$.)

Can we factor an essentiallyIn class, our professor said that working with smooth map into aor essentially smooth map andmorphisms yields an effectively equivalent theory. This motivates my question: Is there a localization?
Certainlygeneral way to lift results from the converse is true, i.e.smooth case to the localization of anyessentially smooth case?

For instance, if $R$-algebra is essentiallyreduced, and $R\to S$ is smooth, since localizations are formally étalethen (except of course when$S$ is reduced. It turns out that the multiplicative system contains zerosame fact is true for essentially smooth maps.)

If not, are Is there any conditions for when we cana good way to "lift" this result to the more general case?

Do essentially smooth ring maps factor into a composition of a smooth map and a localization?

A morphism of rings $R\to S$ is called essentially smooth if it is formally smooth and essentially finitely presented, where essentially finitely presented means that $S$ is the localization of some finitely presented $R$-algebra $T$ at some multiplicative system $A \subset T$, that is, $S=A^{-1}T$.

Can we factor an essentially smooth map into a smooth map and a localization?
Certainly the converse is true, i.e. the localization of any smooth $R$-algebra is essentially smooth, since localizations are formally étale (except of course when the multiplicative system contains zero.)

If not, are there any conditions for when we can?

Lifting results from smooth maps to essentially smooth maps.

Recall that a morphism of rings $R\to S$ is called (essentially) smooth if it is formally smooth and (essentially) finitely presented.

(Note: $R\to S$ is essentially finitely presented provided that $S$ is the localization of some finitely
presented $R$-algebra $T$ at some multiplicative system $A \subset T$, that is, $S=A^{-1}T$.)

In class, our professor said that working with smooth or essentially smooth morphisms yields an effectively equivalent theory. This motivates my question: Is there a general way to lift results from the smooth case to the essentially smooth case?

For instance, if $R$ is reduced, and $R\to S$ is smooth, then $S$ is reduced. It turns out that the same fact is true for essentially smooth maps. Is there a good way to "lift" this result to the more general case?

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Harry Gindi
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Harry Gindi
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Harry Gindi
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